One of well-known conventional techniques is described in “Introduction to Microelectromechanical Microwave Systems”, P122, Artech House Publishers.
The details will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of a switch having a membrane structure composed of membranes. When breaking a signal, as shown in FIG. 2, static electricity is applied to bring a membrane into contact with an electrode, while being not applied in passing a signal.
However, in the conventional device, since a switch is short-circuited to attenuate signals, a reflected wave is generated on the short-circuited surface, whereby excessive power is sent back to an amplifier disposed before the switch and destroys the amplifier. Further, there is another problem that since a membrane and electrode are electrically coupled when not spaced adequately, a passage loss occurs when the switch is ON. Furthermore, when a distance between the membrane and electrode is large, required electrostatic force becomes too large, and an applied voltage becomes too high, resulting in another problem.